Gas chamber based on adjustable gas laser sensor, detection system and detection method

Abstract

The invention relates to a gas chamber based on an adjustable gas laser sensor, a detection system and a detection method in the technical field of coal mine safety monitoring, and the distance between a fixed supporting plate and a movable supporting plate is adjusted through a dynamic optical path adjusting module, so that the length of an optical path is adjusted; laser temperature, detector temperature, environment temperature, gas concentration and laser signal intensity data are synchronously acquired through the data acquisition module and transmitted to the control module, and the control module judges whether light intensity exceeds a preset threshold value or not based on the acquired data and drives the semiconductor refrigeration module to compensate and correct the temperature and the light intensity accordingly. According to the invention, a closed-loop dynamic optical path adjustment mechanism is adopted, the sensitivity and the response speed are improved, the temperature drift is effectively inhibited, and the anti-interference capability is optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine safety monitoring, and in particular to an adjustable gas laser sensor chamber, a detection system and a detection method. Background Art

[0002] Existing laser absorption spectroscopy (TDLAS) gas sensors have the following technical defects: (1) The contradiction between sensitivity and response speed: The traditional gas chamber adopts a fixed optical path design. Although a long optical path (>1m) can improve the sensitivity of low-concentration detection, the response time is long; a short optical path (<0.5m) has a fast response, but cannot meet the needs of trace gas detection; (2) Significant temperature drift interference: The laser wavelength and detector sensitivity are easily affected by ambient temperature fluctuations, resulting in measurement errors (typical temperature drift error ±2% FS); (3) Poor adaptability to multiple scenarios: The gas chamber structure is fixed and cannot be flexibly adjusted according to the gas concentration range or complex working conditions (such as high humidity and strong electromagnetic environment); (4) Insufficient anti-interference ability: Residual gas in the gas path and external electromagnetic noise will reduce the signal-to-noise ratio, which is particularly prominent in multi-gas cross-sensitive scenarios. Summary of the Invention

[0003] In response to the above problems, the present invention provides an adjustable gas laser sensor chamber, a detection system, and a detection method, aiming to solve the following technical problems: (1) Breaking through the contradiction between sensitivity and response speed through dynamic optical path adjustment technology; (2) Through the intelligent temperature control compensation system, the temperature drift interference is suppressed and the detection accuracy is improved; (3) Optimize the anti-interference design of the air chamber to reduce the impact of electromagnetic noise and air path residue.

[0004] The present invention provides an adjustable gas laser sensor chamber, comprising an air chamber body and a group of relatively arranged support plates arranged in the air chamber body, a plurality of reflector groups are respectively arranged on the opposite end surfaces of the two support plates, a laser and a detector are arranged on one of the support plates, the laser can emit laser, the reflector group can reflect the laser, and the detector can receive the reflected laser. The invention also includes a dynamic optical path adjustment mechanism that can adjust the distance between the two support plates, the dynamic optical path adjustment mechanism includes a micro-stepping motor, a guide rail and a slider, the support plate includes a fixed support plate and a movable support plate, the guide rail is a group, and is arranged in parallel between the fixed support plate and the movable support plate, the fixed support plate is fixed to one end of the guide rail, and the movable support plate is slidably connected to the other end of the guide rail through a slider, the micro-stepping motor is connected to the slider, and the micro-stepping motor can drive the movable support plate to slide along the guide rail, thereby adjusting the distance between the fixed support plate and the movable support plate.

[0005] Preferably, the reflector group uses triangular reflective prisms with a gold-plated film or a dielectric film, the reflectivity of the triangular reflective prisms is greater than 95%, and the angle between each triangular reflective prism and the incident light is 45 degrees.

[0006] Preferably, the laser is fixed to the top end of the fixed support plate, and the detector is fixed to the bottom end of the fixed support plate.

[0007] The present invention also provides a detection system for the above-mentioned adjustable gas laser sensor chamber, including a data acquisition module, a control module, a dynamic optical path adjustment module and a semiconductor refrigeration module. The data acquisition module is connected to the laser, the detector and the control module respectively. The data acquisition module is used to collect the laser temperature, the detector temperature, the ambient temperature, the gas concentration and the light intensity. The control module is connected to the laser and the detector through the dynamic optical path adjustment module and the semiconductor refrigeration module. The control module dynamically compensates the optical path and temperature of the laser and the detector according to the collected data.

[0008] In order to accurately collect various data, the data acquisition module includes a laser temperature acquisition module, a detector temperature acquisition module, an ambient temperature acquisition module, a gas concentration acquisition module and a light intensity acquisition module.

[0009] The present invention also provides a detection method for the above-mentioned detection system based on the adjustable gas laser sensor chamber, comprising the following steps: S1, initialize the system; S2, the control module adjusts the distance between the fixed support plate and the movable support plate through the dynamic optical path adjustment module, thereby adjusting the optical path length; S3, the data acquisition module synchronously obtains the laser temperature, detector temperature, ambient temperature, gas concentration and laser signal intensity data (light intensity), and transmits it to the control module; S4, the control module determines whether the light intensity exceeds a preset threshold based on the collected data, and accordingly drives the semiconductor refrigeration module to compensate and correct the temperature and light intensity.

[0010] Furthermore, in step S4, the calibration formula for the light intensity threshold to be determined is as follows: I corrected =I raw −I dark −k env ·(I env −I env0 ) in, I corrected : Calibrated light intensity reading I raw : Detector raw light intensity reading Idark : Dark current equivalent light intensity I env : Ambient light sensor real-time readings I env0 : Ambient light reference value when there is no laser k env : Ambient light coupling coefficient.

[0011] Furthermore, in step S4, compensation correction is performed by changing the output voltage of the semiconductor refrigeration module: V out = kV raw (1 / (1-β*(Lset-Lref)) in, V out : Output voltage value after compensation V raw : Detector original output voltage Lset: target optical path Lref: Reference optical path k: Intrinsic loss of the optical system β: light intensity attenuation coefficient.

[0012] Compared with the prior art, the present invention has the following technical advantages and beneficial effects: (1) Closed-loop dynamic optical path adjustment: Integrate concentration feedback, light intensity monitoring and PID control to achieve a closed loop of "perception-decision-execution"; (2) Improved sensitivity and response speed: In the optical path system, system loss mainly comes from the attenuation of light during refraction. In high-concentration detection environments, a long optical path is not required to improve detection sensitivity. A short optical path mode can be selected to reduce optical path loss and increase response time. When the ambient concentration decreases, the sensitivity can be improved by switching modes and increasing the optical path length. The dynamic optical path switching error is <±3% (achieved through light intensity feedback closed-loop control). (3) Significant temperature drift suppression: Reduce laser wavelength drift, reduce temperature drift error, and improve sensor testing in different application scenarios; (4) Optimization of anti-interference capability: Electromagnetic noise suppression is ≥20dB, and the gas path residual rate is reduced to <0.1%. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic structural diagram of the adjustable gas laser sensor gas chamber of the present invention; Figure 2It is a structural block diagram of the detection system based on the adjustable gas laser sensor chamber of the present invention; Figure 3 The flowchart of the detection method of the detection system based on the adjustable gas laser sensor chamber of the present invention. DETAILED DESCRIPTION

[0014] The following will be combined with the embodiments of the present invention and the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0015] Example 1 like Figure 1 The gas chamber of the adjustable gas laser sensor shown in the figure includes a gas chamber body and a group of relatively arranged support plates 4 arranged in the gas chamber body, wherein the support plates include a fixed support plate and a movable support plate, and a plurality of reflector groups 8 are respectively arranged on the opposite end faces of the two support plates, wherein a circuit board 3 is fixed to the rear side of the fixed support plate, a laser 2 and a detector 5 are arranged on the front side of the fixed support plate, the circuit board 3 is connected to the laser 2 and the detector 5, the laser 2 is fixed to the top end of the fixed support plate, and the detector 5 is fixed to the bottom end of the fixed support plate, the laser 2 can emit laser, the reflector group 8 can reflect the laser, and the detector 5 can receive reflected laser light and also includes a dynamic optical path adjustment mechanism capable of adjusting the distance between the two support plates 4. The dynamic optical path adjustment mechanism includes a micro-stepping motor 1, a guide rail 7, and a slider 6. The guide rails 7 are a set and are arranged in parallel between the fixed support plate and the movable support plate. The fixed support plate is fixed to one end of the two guide rails 7. The top and bottom ends of the movable support plate are respectively slidably connected to the other ends of the two guide rails 7 via the slider 6. The micro-stepping motor 1 is connected to the slider via a lead screw. The micro-stepping motor 1 can drive the movable support plate to slide along the guide rail 7, thereby adjusting the distance between the fixed support plate and the movable support plate.

[0016] The reflector assembly 8 utilizes triangular reflective prisms with a gold-plated or dielectric film. The reflectivity of the triangular reflective prisms is greater than 95%, and the angle between each triangular reflective prism and the incident light is 45 degrees. A micro-stepping motor 1 drives the movable support plate to slide along the guide rail 7, adjusting the distance between the fixed support plate and the movable support plate. For every 1 cm increase in the distance between the fixed support plate and the movable support plate, the optical path increases by 6 cm. A phase-locked amplifier and signal processor are integrated on the circuit board 3 for signal processing. A light intensity feedback sensor is also integrated on the circuit board, automatically switching the optical path mode based on the signal saturation threshold, including a "fast detection mode" and a "high-precision mode."

[0017] In addition, the gas chamber shell is made of aluminum alloy coating (shielding effectiveness ≥ 60 dB), and the internal circuit board is equipped with a ferrite magnetic ring; the inner wall of the gas path is coated with polytetrafluoroethylene (adsorption rate <0.01%) to reduce gas adsorption; high-transmittance, low-reflectivity anti-reflection film windows and high-quality reflectors (high reflectivity, low scattering) are used to reduce light energy loss and stray light; the inner wall of the gas chamber is coated with a high-absorption, low-reflectivity black coating (Actin Black) to reduce the probability of stray light reaching the detector; the inner wall of the gas chamber, seals and other parts that come into contact with the gas are made of inert materials, including but not limited to 316L stainless steel, Hastelloy alloy, PEEK polymer, PTFE polymer, to reduce gas adsorption / desorption and chemical reactions, ensure response speed and measurement stability, and reduce background interference.

[0018] Example 2 like Figure 2 The detection system shown is used for the above-mentioned adjustable gas laser sensor chamber, including a data acquisition module, a control module, a dynamic optical path adjustment module and a semiconductor refrigeration module. The data acquisition module is connected to the laser, the detector and the control module respectively. The data acquisition module is used to collect the laser temperature, the detector temperature, the ambient temperature, the gas concentration and the light intensity. The control module is connected to the laser and the detector through the dynamic optical path adjustment module and the semiconductor refrigeration module. The control module dynamically compensates the optical path and temperature of the laser and the detector according to the collected data.

[0019] The data acquisition module includes a laser temperature acquisition module, a detector temperature acquisition module, an ambient temperature acquisition module, a gas concentration acquisition module and a light intensity acquisition module; The semiconductor refrigeration module can use a semiconductor cooler TEC, and through the TEC cooling plate combined with the PID algorithm (temperature control accuracy ±0.01°C), the laser wavelength is stabilized, and the semiconductor cooler is driven by a constant current source (temperature control accuracy ±0.1°C) to suppress the dark current drift of the detector; the data acquisition module can use a high-precision sensor; the ambient temperature sensor collects the ambient temperature in real time and corrects the temperature drift error through a polynomial fitting algorithm.

[0020] Example 3 like Figure 3 A detection method for the above-mentioned detection system based on the adjustable gas laser sensor chamber is shown, comprising the following steps: S1, initialize the system; S2, the control module adjusts the distance between the fixed support plate and the movable support plate through the dynamic optical path adjustment module, thereby adjusting the optical path length; S3, the data acquisition module collects laser temperature, detector temperature, ambient temperature, gas concentration and light intensity, and sends the collected data to the control module; S4, the control module determines the light intensity threshold based on the collected data. In terms of optical path switching, the determined light intensity threshold is easily affected by ambient light and dark current. The calibration formula for the required light intensity threshold is as follows: I corrected =I raw −I dark −k env ·(I env −I env0 ) in, I corrected : Calibrated light intensity reading I raw : Detector raw light intensity reading I dark : Dark current equivalent light intensity I env : Ambient light sensor real-time readings I env0 : Ambient light reference value when there is no laser k env : Ambient light coupling coefficient, about 0.92 Considering that the intensity of light received by the detector will be affected during the change of optical path, compensation correction is performed by changing the output voltage of the semiconductor refrigeration module according to the light intensity threshold: V out = kV raw (1 / (1-β*(Lset-Lref)) in, V out : Output voltage value after compensation V raw : Detector original output voltage Lset: target optical path (adjusted laser-reflector distance) Lref: Reference optical path (initial position, usually the shortest optical path) k: Intrinsic loss of the optical system β: light intensity attenuation coefficient; Initially, long optical path detection can be used. If the signal amplitude exceeds a threshold (such as 90% of the range), it will automatically switch to short optical path, demodulate the concentration based on the second harmonic (2f / 1f) signal, and eliminate noise in combination with the Kalman filter algorithm.

[0021] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. An adjustable gas laser sensor chamber, comprising a chamber body and a set of opposing support plates disposed within the chamber body, with a plurality of reflector groups disposed on opposing end surfaces of the two support plates, one of the support plates being provided with a laser and a detector, wherein the laser is capable of emitting laser light, the reflector group is capable of reflecting the laser light, and the detector is capable of receiving the reflected laser light, and wherein: It also includes a dynamic optical path adjustment mechanism capable of adjusting the distance between the two support plates, the dynamic optical path adjustment mechanism includes a micro-stepping motor, a guide rail and a slider, the support plate includes a fixed support plate and a movable support plate, the guide rail is a group, and is arranged in parallel between the fixed support plate and the movable support plate, the fixed support plate is fixed to one end of the guide rail, and the movable support plate is slidably connected to the other end of the guide rail through a slider, the micro-stepping motor is connected to the slider, and the micro-stepping motor can drive the movable support plate to slide along the guide rail, thereby adjusting the distance between the fixed support plate and the movable support plate.

2. The adjustable gas laser sensor chamber according to claim 1, characterized in that: The reflector group adopts a triangular reflective prism with a gold-plated film or a dielectric film. The reflectivity of the triangular reflective prism is greater than 95%, and the angle between each triangular reflective prism and the incident light is 45 degrees.

3. The adjustable gas laser sensor chamber according to claim 1, characterized in that: The laser is fixed on the top end of the fixed support plate, and the detector is fixed on the bottom end of the fixed support plate.

4. A detection system based on an adjustable gas laser sensor chamber according to any one of claims 1 to 3, characterized in that: It includes a data acquisition module, a control module, a dynamic optical path adjustment module and a semiconductor refrigeration module. The data acquisition module is connected to the laser, the detector and the control module respectively. The data acquisition module is used to collect the laser temperature, the detector temperature, the ambient temperature, the gas concentration and the light intensity. The control module is connected to the laser and the detector through the dynamic optical path adjustment module and the semiconductor refrigeration module. The control module dynamically compensates the optical path and temperature of the laser and the detector according to the collected data.

5. The detection system based on an adjustable gas laser sensor chamber according to claim 4, characterized in that: The data acquisition module includes a laser temperature acquisition module, a detector temperature acquisition module, an ambient temperature acquisition module, a gas concentration acquisition module and a light intensity acquisition module.

6. A detection method for a detection system based on an adjustable gas laser sensor chamber as claimed in claim 5, characterized in that: The steps include: S1, initialize the system; S2, the control module adjusts the distance between the fixed support plate and the movable support plate through the dynamic optical path adjustment module, thereby adjusting the optical path length; S3, the data acquisition module synchronously obtains the laser temperature, detector temperature, ambient temperature, gas concentration and laser signal intensity data, and transmits them to the control module; S4, the control module determines whether the light intensity exceeds a preset threshold based on the collected data, and accordingly drives the semiconductor refrigeration module to compensate and correct the temperature and light intensity.

7. The detection method of the detection system based on the adjustable gas laser sensor chamber according to claim 6, characterized in that: In step S4, the calibration formula for the light intensity threshold to be determined is as follows: I corrected =I raw −I dark −k env ·(I env −I env0 ) in, I corrected : Calibrated light intensity reading I raw : Detector raw light intensity reading I dark : Dark current equivalent light intensity I env : Ambient light sensor real-time readings I env0 : Ambient light reference value when there is no laser k env : Ambient light coupling coefficient.

8. The detection method of the detection system based on the adjustable gas laser sensor chamber according to claim 7, characterized in that: In step S4, compensation correction is performed by changing the output voltage of the semiconductor refrigeration module: V out = k V raw (1 / (1-β*(Lset- Lref)) in, V out : Output voltage value after compensation V raw : Detector original output voltage Lset: target optical path Lref: Reference optical path k: Intrinsic loss of the optical system β: light intensity attenuation coefficient.

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